Circuit Symbols for MOSFET
A range of symbols are employed for the MOSFET. The basic design is usually a line for the channel along with the source and drain leaving it at right angles and then bending back at right angles into similar direction as the channel. Occasionally three line segments are employed for enhancement mode and a solid line for depletion mode. One more line is drawn parallel to the channel for the gate.
The bulk connection, if displayed, is shown connected to the back of the channel with an arrow pointing out PMOS or NMOS. Arrows all the time point from P to N, thus an NMOS (N-channel in P-well or P-substrate) has the arrow pointing in (from the bulk to the channel). If the bulk is associated to the source (as is usually the case with discrete devices) it is occasionally angled to meet up with the source leaving the transistor. If the bulk is not shown (as is frequently the case in IC design as they are usually common bulk) an inversion symbol is sometimes employed to point out PMOS, alternatively an arrow on the source may be employed in similar way as for bipolar transistors (out for nMOS, in for pMOS).
Evaluation of enhancement-mode and depletion-mode MOSFET symbols, with JFET symbols (drawn with source and drain ordered like that higher voltages appear higher on the page than as compared to the lower voltages):
For the symbols where the bulk, or body, terminal is displayed, it is here shown internally connected to the source. This is a common configuration, but via no means the only important configuration. Generally, the MOSFET is a four-terminal device, and in integrated circuits many of the MOSFETs share a body connection not essentially related to the source terminals of all the transistors.